1. Field of the Invention
The invention relates to a lighting device and a lighting method for a vehicle. More particularly, the invention relates to a lighting device and a lighting method for a vehicle which control the light distribution of a headlight.
2. Description of the Related Art
Various related technologies of controlling the light distribution of a headlight of a vehicle in order to secure a forward visibility for the vehicle driver during nighttime travel.
For example, a technology described in Japanese Patent Application Publication No. 2006-248246 (JP-A-2006-248246) includes lighting range control means for controlling a range of lighting the road, and a lane mark sensing means for sensing a lane mark on the road. When the lane mark sensing means does not sense a lane mark, the technology performs a control of broadening the lighting range toward a region in which no lane mark is sensed. Thus, the lighting range is expanded toward a region in which no lane mark exists, and brighter lighting is provided for the region of high need for safety checking on a travel road ahead without a lane mark, such as an intersection, a branching road, a merging road, a curve, etc.
According to the foregoing technology described in Japanese Patent Application Publication No. 2006-248246 (JP-A-2006-248246), on a curve where no lane mark is sensed, or the like, the lighting range is expanded toward a region in which no lane mark is sensed, which can result in light being radiated to a lane mark that was not sensed. In the case where light is radiated to a lane mark such as a white line or the like, the white line, high in reflectance, stands out, so that the vehicle driver may sometimes misconceive that the entire field of view is visible despite insufficient visibility of sites other than the white line. In such a case, the vehicle driver, thinking that the visibility is good, may sometimes increase the vehicle speed. Thus, there is a room for betterment, from the viewpoint of safety and restraint of the vehicle speed.